Abstract: Disclosed is a copper foil—for printed circuit boards—which is especially excellent in soft etching property and also superior in such properties as heat discoloration resistance, rust-proofing and solder-ability. The copper foil for printed circuit boards comprising a first layer formed by applying 12 to 50 mg/m2 of a sulfur-contained zinc alloy containing 0.1 to 2.5 percent by weight of sulfur on the surface on at least one side of the copper foil and a second layer formed of a chromate layer on the first layer by applying 0.5 to 2.5 mg/m2 of chromium and, if necessary, 1.5 to 6 mg/m2 of phosphorus.

Abstract: Disclosed is a process of treating the surface of copper foil without using harmful elements such as arsenic, selenium and tellurium unlike in the prior art. It is possible to, in an easy way, obtain a uniform rough condition and low roughness and produce a high peel strength to such resin base materials as polyimide resin which is weak in peel strength. The process comprises a roughening treatment involving a cathodic electrolysis of at least one side of copper foil near or above the limiting current density in an electrolytic bath containing titanium ions and tungsten ions and prepared by adding sulfuric acid and copper sulfate so as to have copper protrusions deposited and then coating the depositions with copper or copper alloy in a cathodic electrolysis, followed by giving to the surface of the above-mentioned copper or the copper alloy at least one rust-proofing treatment.

Abstract: Disclosed is a copper foil—for printed circuit boards—which is especially excellent in soft etching property and also superior in such properties as heat discoloration resistance, rust-proofing and solder-ability. The copper foil for printed circuit boards comprising a first layer formed by applying 12 to 50 mg/m2 of a sulfur-contained zinc alloy containing 0.1 to 2.5 percent by weight of sulfur on the surface on at least one side of the copper foil and a second layer formed of a chromate layer on the first layer by applying 0.5 to 2.5 mg/m2 of chromium and, if necessary, 1.5 to 6 mg/m2 of phosphorus.

Abstract: Disclosed is a process of treating the surface of copper foil without using harmful elements such as arsenic, selenium and tellurium unlike in the prior art. It is possible to, in an easy way, obtain a uniform rough condition and low rougheness and produce a high adhesive strength to such resin base materials as polymide resin which is weak in adhesive strength. The process comprises a roughening treatment involving a cathodic electrolysis of at least one side of copper foil near or above the limiting current density in an electrolytic bath containing titanium ions and tungsten ions and prepared by adding sulfuric acid and copper sulfate so as to have copper protrusions deposited and then coating the depositions with copper or a copper alloy in a cathodic electrolysis, followed by giving to the surface of the above-mentioned copper or the copper alloy at least one of the following rust-proofing treatments—chromate treatment, organic rust-proofing treatment and silane coupling agent treatment.